Systems and methods for time-based parallel robotic operation

ABSTRACT

Example systems and methods may allow for parallel operation of robotic devices within a workcell, such as industrial robots controlled to manufacture an output product. One example method includes receiving ordered sequences of operations for a plurality of corresponding robotic devices, determining time-based sequences of operations for each of the robotic devices, where a time-based sequence of operations indicates positions within the workcell at corresponding timesteps of a global timeline, determining one or more potential collisions involving the robotic devices that would result from parallel execution of the time-based sequences of operations within the workcell, modifying the time-based sequences of operations in order to prevent the one or more potential collisions, and providing instructions for parallel execution of the modified time-based sequences of operations at timesteps of the global timeline by the robotic devices within the workcell.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority to U.S. Provisional patentapplication Ser. No. 62/001,521, filed on May 21, 2014, and entitled“Systems and Methods for Time-Based Parallel Robotic Operation,” whichis herein incorporated by reference as if fully set forth in thisdescription.

BACKGROUND

Unless otherwise indicated herein, the materials described in thissection are not prior art to the claims in this application and are notadmitted to be prior art by inclusion in this section.

Automated manufacturing processes may involve the use of one or morerobotic devices that may be used to construct an output product, such asa car, a wall, a piece of furniture, or any number of other physicalfabrications. The robotic devices may be equipped withend-effector-mounted tools, such as a gripper or a drill, that may beused during a construction process. The robotic devices may beprogrammed with sequences of specific motion commands and commands forother operations in order to cause the robotic devices to complete amanufacturing process.

SUMMARY

The present disclosure provides methods and apparatuses that may help toallow for time-based, parallel execution of robot operations within aworkcell. The workcell may be a manufacturing environment or otherenvironment containing one or more robotic devices and/or othercomponents to enable an automated robotic process. Within examples,sequential operations may be received that indicate sequences of targetpositions for a plurality of robotic devices to move through within theworkcell. Time-based sequences of operations may then be determined foreach robotic device. The time-based sequences may indicate positions ofthe robotic devices at timesteps of a global timeline, including thereceived target positions. Possible collisions resulting from parallelexecution of the time-based sequences may be identified, andmodifications of the time-based sequences may be determined to preventthe collisions. The modified time-based sequences of operations may thenbe provided to the robotic devices for parallel execution within theworkcell.

In one example, a method is provided that includes receiving orderedsequences of operations for a plurality of corresponding roboticdevices, where an ordered sequence of operations includes an orderedsequence of target positions within a workcell. The method may alsoinclude determining, by a computing device, time-based sequences ofoperations for each of the robotic devices, where a time-based sequenceof operations indicates positions within the workcell at correspondingtimesteps of a global timeline, where the positions within a time-basedsequence of operations include the target positions from the orderedsequence of operations for the corresponding robotic device. The methodmay further include determining one or more potential collisionsinvolving the robotic devices that would result from parallel executionof the time-based sequences of operations within the workcell. Themethod may additionally include modifying the time-based sequences ofoperations in order to prevent the one or more potential collisions. Themethod may further include providing instructions for parallel executionof the modified time-based sequences of operations at timesteps of theglobal timeline by the robotic devices within the workcell.

In a further example, a system including a non-transitorycomputer-readable medium and program instructions stored on thenon-transitory computer-readable medium is disclosed. The programinstructions may be executable by at least one processor to receiveordered sequences of operations for a plurality of corresponding roboticdevices, where an ordered sequence of operations comprises an orderedsequence of target positions within a workcell. The program instructionsmay further be executable to determine time-based sequences ofoperations for each of the robotic devices, where a time-based sequenceof operations indicates positions within the workcell at correspondingtimesteps of a global timeline, where the positions within a time-basedsequence of operations include the target positions from the orderedsequence of operations for the corresponding robotic device. The programinstructions may also be executable to determine one or more potentialcollisions involving the robotic devices that would result from parallelexecution of the time-based sequences of operations within the workcell.The program instructions may additionally be executable to modify thetime-based sequences of operations in order to prevent the one or morepotential collisions. The program instructions may further be executableto provide instructions for parallel execution of the modifiedtime-based sequences of operations at timesteps of the global timelineby the robotic devices within the workcell.

In another example, a non-transitory computer readable medium havingstored therein instructions, that when executed by a computing system,cause the computing system to perform functions is disclosed. Thefunctions may include receiving ordered sequences of operations for aplurality of corresponding robotic devices, where an ordered sequence ofoperations includes an ordered sequence of target positions within aworkcell. The functions may also include determining time-basedsequences of operations for each of the robotic devices, where atime-based sequence of operations indicates positions within theworkcell at corresponding timesteps of a global timeline, where thepositions within a time-based sequence of operations include the targetpositions from the ordered sequence of operations for the correspondingrobotic device. The functions may further include determining one ormore potential collisions involving the robotic devices that wouldresult from parallel execution of the time-based sequences of operationswithin the workcell. The functions may additionally include modifyingthe time-based sequences of operations in order to prevent the one ormore potential collisions. The functions may further include providinginstructions for parallel execution of the modified time-based sequencesof operations at timesteps of the global timeline by the robotic deviceswithin the workcell.

In yet another example, a system may include means for receiving orderedsequences of operations for a plurality of corresponding roboticdevices, where an ordered sequence of operations includes an orderedsequence of target positions within a workcell. The system may alsoinclude means for determining time-based sequences of operations foreach of the robotic devices, where a time-based sequence of operationsindicates positions within the workcell at corresponding timesteps of aglobal timeline, where the positions within a time-based sequence ofoperations include the target positions from the ordered sequence ofoperations for the corresponding robotic device. The system may furtherinclude means for determining one or more potential collisions involvingthe robotic devices that would result from parallel execution of thetime-based sequences of operations within the workcell. The system mayadditionally include means for modifying the time-based sequences ofoperations in order to prevent the one or more potential collisions. Thesystem may further include means for providing instructions for parallelexecution of the modified time-based sequences of operations attimesteps of the global timeline by the robotic devices within theworkcell.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the figures and the followingdetailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of a manufacture control system, accordingto an example embodiment.

FIG. 2A shows a view of a robot with 7 degrees of freedom, according toan example embodiment.

FIG. 2B shows a view of a robot with an attached gripper, according toan example embodiment.

FIG. 2C shows a view of a robot with an attached spindle, according toan example embodiment.

FIG. 3A shows a view of a tool rack, according to an example embodiment.

FIG. 3B shows a view of a tool rack and two robots, according to anexample embodiment.

FIG. 4A shows a graphical interface with a 3D model, according to anexample embodiment.

FIG. 4B shows additional graphical interfaces with 3D models, accordingto an example embodiment.

FIG. 5 illustrates a node-based graphical interface and a visualizationof a building process, according to an example embodiment.

FIG. 6A illustrates a toolbar for a graphical interface, according to anexample embodiment.

FIG. 6B illustrates an organization of digital tools, according to anexample embodiment.

FIG. 6C is a block diagram of an example workflow, according to anexample embodiment.

FIG. 7 is a block diagram of an example method, according to an exampleembodiment.

FIG. 8A illustrates an example of sequential robotic operation,according to an example embodiment.

FIG. 8B illustrates an example of time-based robotic operation,according to an example embodiment.

FIG. 8C illustrates motion paths of two robotic devices operating inparallel, according to an example embodiment.

FIG. 8D illustrates alternative motion paths for the robotic devices inFIG. 8C, according to an example embodiment.

FIG. 8E illustrates further alternative motion paths for the roboticdevices in FIG. 8C, according to an example embodiment.

DETAILED DESCRIPTION

Example methods and systems are described herein. Any example embodimentor feature described herein is not necessarily to be construed aspreferred or advantageous over other embodiments or features. Theexample embodiments described herein are not meant to be limiting. Itwill be readily understood that certain aspects of the disclosed systemsand methods can be arranged and combined in a wide variety of differentconfigurations, all of which are contemplated herein.

Furthermore, the particular arrangements shown in the Figures should notbe viewed as limiting. It should be understood that other embodimentsmight include more or less of each element shown in a given Figure.Further, some of the illustrated elements may be combined or omitted.Yet further, an example embodiment may include elements that are notillustrated in the Figures.

I. OVERVIEW

Example systems and methods may help to provide for parallel operationof robotic devices within a workcell, such as industrial robotscontrolled to manufacture an output product. Sequences of robotoperations, including robot movements and tool actions, may first beprovided corresponding to different robotic devices within the workcell.In some instances, these sequences may be generated by a user from asoftware authoring environment. In other examples, sequences forindividual robots may have been previously programmed and stored forlater execution. The sequences of robot operations may indicatesequences of target positions (e.g., positions with six degrees offreedom) for the effector of a robotic device to progress through withinthe workcell. Within examples, sequences of robot operations may beconverted into time-based sequences with reference to a global timelineto allow for parallel execution within the workcell.

In further examples, time-based sequences of operations for the roboticdevices may indicate positions of an end effector of one of the roboticdevices at timestamps along the global timeline. In some cases, aparticular time interval may separate consecutive timestamps. Forinstance, in one example, the position of each robotic device may bedetermined every 12 milliseconds along the timeline. In other examples,a different time resolution may be used, possibly depending on availablehardware or communication systems within a particular workcell.

In additional examples, the time-based sequence of operations for arobotic device may include the target positions from the correspondingsequence of operations for the robotic device. For example, the targetpositions may define a motion path through the workcell for the roboticdevice to follow (e.g., during a construction process). The time-basedsequence may include the target positions in order to cause the roboticdevice to move through the same motion path.

In further examples, additional positions for the robotic device may beinserted between consecutive target positions in determining thetime-based sequence for a robotic device. For instance, a time intervalof 12 milliseconds may be used for a time-based sequence, but thesequential operations for a robotic device may only include targetpositions that can be reached by the robotic device roughly everysecond. In such an example, positions may be determined in betweenconsecutive target positions in order to provide a smoother motion pathfor the robotic device. For instance, instead of moving through straightlines connecting consecutive target positions, continuous curves may beused. In additional examples, positions may be selected in order tominimize the amount of time required for the robotic device to travelfrom one target position to the next.

In further examples, possible collisions resulting from parallelexecution of robot operations by multiple robotic devices within aworkcell may be predicted. For instance, the time-based sequences ofoperations for several robotic devices may be synchronized to a commonclock with a particular timestep resolution. Accordingly, the positionof each robotic device within the workcell may be determined attimesteps along the global timeline and used to determine whencollisions may occur. When possible collisions are detected, one or moreof the time-based sequences of operations may be modified in order toallow for parallel execution without collision.

In some examples, time-based sequences of operations may be modified toavoid collisions while attempting to minimize the amount of timerequired to complete a process (e.g., a manufacturing process). In oneexample, the rate of operation of one or more of the robotic devices maybe modified at one or more points along the global timeline. Forinstance, a particular robot may be slowed down in order to avoidcollision with a second acting robot in the workcell. In furtherexamples, velocity curves relative to the global timeline may bedetermined for each of the robotic devices in an effort to allow therobotic devices to collectively operate as fast as possible whileavoiding any collisions in the workcell.

In other examples, one or more time-based sequences of operations may bemodified to avoid collisions in other ways as well or instead. Forinstance, operations may be inserted to cause one or more of the devicesto hold position within the workcell for a particular length of timewithin the global timeline. For example, a first robot may be commandedto hold position until a second robot completes a particular motion paththrough the workcell, in additional examples, positions between targetpositions within the time-based sequences of operations may bedetermined in order to avoid collisions, independently or in conjunctionwith timing modification. For instance, a first robot may be commandedto move around an area occupied by another robot to reach a particulartarget position.

In further examples, the sequential operations for the robotic devicesmay include sync points corresponding to operations within each robot'ssequence of operations that must be reached before any of the robots cancontinue executing operations. For instance, sync points may be used toensure no collisions occur from simultaneous operation within aworkcell. By converting to time-based sequences of operations, some syncpoints may not be necessary to avoid collisions in some examples.Instead, collision detection may be done based on positions of roboticdeices at timesteps along the global timeline. However, in someexamples, certain operations may still need to be synchronized intime-based mode. For example, two robotic devices may be operating on aparticular component within the workspace (e.g., a first robotic devicemay insert a screw into a board being held by a second robotic device).In such examples, these sync points may be identified as anchor pointsrequiring synchronization in time-based mode while other sync points maybe removed when converting to time-based mode.

Example systems, including various software and hardware components,will be described below. It should be understood that alternativesystems, which may omit certain components, combine components, and/oradd additional components, may also employ the disclosed methods in someexamples as well.

II. EXAMPLE CONTROL SYSTEMS

Example embodiments may provide for motion planning and control ofmulti-axis robotic systems for use in the manufacturing and makingindustries. Example design-to-production systems may allow users tochange parameters describing an output product on the front end, withthe effects propagated through to a product manufactured by one or morerobotic devices using one or more tools. In some examples, users may beprovided with a graphical interface that allows for the configuration ofthe robot actors using a diverse toolset in order to automate thebuilding process. In further examples, robot motions may be abstractedso that users don't have to program specific robot commands (e.g.,motion commands or tool commands) in order to control the buildingprocess. Accordingly, users may be able to design a building processwithout specific knowledge of commands for particular types of robots.Additionally, users may be provided with one or more interfaces thatallow for varying amounts of control over specific robot operationswithin a manufacturing process, during offline motion programming and/orduring runtime.

In further examples, users may be provided with a three-dimensional (3D)modeling graphical interface that allows the user to alter one or morevariables describing a physical workcell and/or a desired output productthat affect a building process in the physical world. Additionally, theuser interface may provide abstract ways to represent physical objectsdigitally as nodes within a software environment. In particular, theuser experience may enable users to select from an array of tools whichcan be configured and combined in a number of different ways to controldifferent types of robot actors and hardware components within aphysical workcell.

In further examples, the physical workcell may include a physical stageor stages on which a physical building process is planned or isoccurring within the physical world. In some examples, the physicalworkcell may include a variety of different robot actors and otherhardware components as well as physical materials that may be used inthe building process. In further examples, the physical workcell maycontain a tool rack and/or an automated tool changer. In additionalexamples, the physical workcell may contain one or more different typesof sensors. Also, the physical workcell may include any number ofdifferent dimensions, including platforms for particular buildingactivities.

It should be understood that the present disclosure is not to be limitedin terms of the particular embodiments described in this application,which are intended as illustrations of various aspects. Numerouscomponents of example manufacturing systems are described herein.Systems that contain only some of those components or any combination ofsuch components are contemplated as well. Many modifications andvariations can be made without departing from the spirit and scope ofthe disclosed systems and methods. Functionally equivalent methods andapparatuses within the scope of the disclosure, in addition to thoseenumerated herein, will be apparent to those skilled in the art.

Example embodiments may involve use of a manufacture control system tocreate automated programming of robotics arms during a building process.FIG. 1 describes an example manufacture control system 100. Manufacturecontrol system 100 may be part of a manufacturing environment used tocontrol one or more robotic devices to use one or more tools toconstruct some output product. Manufacture control system 100 maycomprise a master control 10, input and feedback systems 20, systemdevices 40, and safety systems 90. From the most basic perspective,manufacture control system 100 may function when an input system 20provides instructions to one of system devices 40 via master control 10.

In one potential embodiment as part of a manufacture control system 100,input and feedback systems 20 may include a database 22, a master input24, a software control 26, and an independent manual control 28. As partof the input and feedback systems 20, database 22 may operate to providea set of timing and position data to direct all or a portion of deviceactors 42, 44 within system devices 40. Two device actors 42, 44 areshown in FIG. 1, but any number of device actors could be used withinmanufacture control system 100. Alternatively, database 22 may storedata being created by manual or individual movement or data inputrelated to operation and function of device actors 42, 44. Database 22may also store data created independently of device actors 42, 44, suchas data created using software modeling features of a software control26.

A master input 24 may be any device that functions to operate all of thedevice actors 42, 44 associated with a particular building process beingexecuted by manufacture control system 100. Master input 24 may functionby sending input control signals to master control 10. Master control 10may then adapt the signal from master input 24 to send individualcontrol signals to a plurality of robot actors operating as deviceactors 42, 44 for a particular manufacturing process. In one potentialembodiment, every individual device of device actors 42, 44 may beprovided a control signal from master control 10 when a signal isreceived from master input 24, including a signal to maintain a statusquo or non-action to devices that are not operating as device actors 42,44 for a particular part of the manufacturing process. In an alternativeembodiment, a portion of the device actors 42, 44 connected as part ofmanufacture control system 100 may not be sent any signal from mastercontrol 10 as part of the operation of motion control system 100 for aparticular part of the manufacturing process.

In some examples, software control 26 may act as a replacement formaster input 24 in sending control signals to the plurality of deviceactors 42, 44 via the master control 10. Alternately, software control26 may control individual devices from among device actors 42, 44 tocontrol particular operations of the individual device. In otherpotential embodiments, software control 26 may function to model thebehavior of individual devices of device actors 42, 44 within a virtualmodeling environment representative of a physical workcell. In such anembodiment, software control 26 may contain a software model for anindividual device, which allows control signals to be created for thedevice without actually sending the control signals to the device. Thecontrol signals may then be stored in the software control 26, indatabase 22, within a computer memory component that is part of mastercontrol 10, or within computer memory that is part of the device ofdevice actors 42, 44 for which the controls are being created. After thecontrol signal is created by software control 26 and propagated to theappropriate storage location, a master control signal from softwarecontrol 26 or from master input 24 may activate the control signal forthe individual device to act in conjunction with other device actors 42,44.

In further examples, certain devices of device actors 42, 44 mayadditionally have an independent manual control 28. As described abovewith respect to software control 26, control signals for an individualdevice may be created in software modeling. In addition or instead, adevice may have independent manual control 28 that may be used tooperate a device of device actors 42, 44. When a set of instructions isbeing created for an entire manufacturing process, the independentmanual control 28 may be given input commands over time that arerecorded to database 22 or a memory device of master control 10. Duringcreation of a set of instructions using independent manual control 28,the independent manual control 28 may communicate directly with theassociated device of device actors 42, 44. Alternatively, theindependent manual control 28 may send a control signal to mastercontrol 10, which then conveys the signal to the associated device ofdevice actors 42, 44.

The control signal may then be created either from the signal of theindependent manual control 28 (e.g., a separate user interface), or froma measured feedback reading created by the operation of the associateddevice. Additionally, although in many situations, it may be preferableto have the independent manual control 28 actually control theassociated device during control signal creation in real time, controlsignals may instead be created without controlling the device. Forexample, if input signals are expected for certain time marks, anindependent manual control 28 may be operated independent of the relateddevice, and the control operation may be recorded. Accordingly,instructions for individual device actors of device actors 42, 44 fromindependent manual control may be integrated into a building process aspart of manufacture control system 100.

In further examples, master control 10 may allow for real-time controlof components of a building system by providing a link between a virtualworld (e.g., software control 26) and the physical world (e.g., aphysical workcell containing device actors 42, 44). Accordingly,movements of a physical robot within the physical world may be used todrive the current position of a corresponding virtual robot in realtime. Similarly, movements of a virtual robot may be used to drive thecurrent position of a physical robot in the physical world as well orinstead.

In one potential embodiment, individual control signals for specificdevice actors may be coordinated into a single file within a memory of amaster control with a common base time provided by a master clock withinthe master control. During operation, the master control may extractcontrol signals for each device actor and provide individual controlsignals to each device actor at the appropriate intervals. In analternative embodiment, the master control signals maintain separateindividual control signal files and timing data for different deviceactors, and synchronize the different control signals separately fromthe individual control files.

In another alternative embodiment, the control data for a portion of thedevice actors may be transferred by a master control to a memory withinan associated individual device actor. During operation, device actorshaving control data within memory may receive a synchronization signalthat indicates a location in a global timeline, a rate of progressthrough a global timeline, or both.

Network support may also enable communications from master control 10 toone or more of system devices 40. In one potential embodiment, a networkmay comprise an EtherCAT network operating according to IEEE 1588. Insuch an embodiment, packets may be processed on the fly using a fieldbus memory management unit in each slave node. Each network node mayread the data addressed to it, while the telegram is forwarded to thenext device. Similarly, input data may be inserted while the telegrampasses through. The telegrams may only be delayed by a few nanoseconds.On the master side, commercially available standard network interfacecards or an on-board Ethernet controller can be used as a hardwareinterface. Using these interfaces, data transfer to the master controlvia direct memory access may be achieved with no CPU capacity taken upfor the network access. The EtherCAT protocol uses an officiallyassigned Ether Type inside the Ethernet Frame. The use of this EtherType may allow transport of control data directly within the Ethernetframe without redefining the standard Ethernet frame. The frame mayconsist of several sub-telegrams, each serving a particular memory areaof the logical process images that can be up to 4 gigabytes in size.Addressing of the Ethernet terminals can be in any order because thedata sequence may be independent of the physical order. Broadcast,multicast, and communication between slaves are possible.

Transfer directly in the Ethernet frame may be used in cases whereEtherCAT components are operated in the same subnet as the mastercontroller and where the control software has direct access to theEthernet controller. Wiring flexibility in EtherCAT may be furthermaximized through the choice of different cables. Flexible andinexpensive standard Ethernet patch cables transfer the signalsoptionally in Ethernet mode (100BASE-TX) or in E-Bus (LVDS) signalrepresentation. Plastic optical fiber (POF) can be used in specialapplications for longer distances. The complete bandwidth of theEthernet network, such as different fiber optics and copper cables, canbe used in combination with switches or media converters. Fast Ethernet(100BASE-FX) or E-Bus can be selected based on distance requirements.

Further, such an embodiment using EtherCAT supports an approach forsynchronization with accurate alignment of distributed clocks, asdescribed in the IEEE 1588 standard. In contrast to fully synchronouscommunication, where synchronization quality suffers immediately in theevent of a communication fault, distributed aligned clocks have a highdegree of tolerance from possible fault-related delays within thecommunication system. Thus, data exchange may be completely done inhardware based on “mother” and “daughter” clocks. Each clock can simplyand accurately the other clocks' run-time offset because thecommunication utilizes a logical and full-duplex Ethernet physical ringstructure. The distributed clocks may be adjusted based on this value,which means that a very precise network-wide time base with a jitter ofsignificantly less than 1 microsecond may be available.

However, high-resolution distributed clocks are not only used forsynchronization, but can also provide accurate information about thelocal timing of the data acquisition. For example, controls frequentlycalculate velocities from sequentially treasured positions. Particularlywith very short sampling times, even a small temporal jitter in thedisplacement measurement may lead to large step changes in velocity. Inan embodiment comprising EtherCAT, the EtherCAT expanded data types(timestamp data type, oversampling data type) may be introduced. Thelocal time may be linked to the measured value with a resolution of upto 10 ns, which is made possible by the large bandwidth offered byEthernet. The accuracy of a velocity calculation may then no longerdepend on the jitter of the communication system.

Further, in an embodiment where a network comprises EtherCAT, a hotconnect function may enable parts of the network to be linked anddecoupled or reconfigured “on the fly”. Many applications require achange in I/O configuration during operation. The protocol structure ofthe EtherCAT system may take account these changing configurations.

In further examples, safety systems 90 may be provided for preventativesafety in detecting potential collisions between device actors inmodeling the motion of the actors through a global timeline. Further,such modeling through a global timeline may be used to set safetyparameters for safety systems 90. Modeling of locations and velocitiesof device actors through a global timeline may enable identification ofunsafe zones and unsafe times in an area of a physical workcell. Such anidentification may be used to set sensing triggers of object detectorsthat are part of an example safety system. For example, if an areawithin 5 feet of a certain device actor is determined to be at risk ofcollision, and a buffer zone of 10 additional feet is required to insuresafety during operation, a LIDAR detector may be configured to detectunexpected objects and movement within a 15 foot area of the deviceactor during operation, and to automatically create a safety shutdown ifan object is detected. In an alternative embodiment, the LIDAR detectormay be configured to create a warning signal if an object is detected ina periphery of the danger zone, and only to create a shutdown if thedetected object is moving toward a potential impact zone.

In an alternate embodiment, safety systems 90 may include modeling ofactors and models of defined safe zones. Analysis of the motion of theactors in software control may allow a modeled safety check to see ifany actor collides with a defined safe zone. In some examples, safezones may be defined by entry of fixed volumes of space into a softwarecontrol, by image capture of a physical workcell. Safe zones may also bedefined to be variable based on a detected motion, jerk, velocity, oracceleration of an object in a safe zone. In an alternate embodiment, asafe zone may be defined by input from transponder device data. Forexample, a transponder location device may be attached to a roboticdevice actor, and a safe zone defined by a distance from thetransponder. The transponder may feed location data to software control,which may update safe zones within a software control or within a mastersafety control. In another embodiment, fixed safe zones may be definedwithin software control, and published prior to a safety PLC within amaster safety control prior to operation of a building process.

In some examples, system devices 40 may additionally include one or moresensors 46 and 48, such as laser-based, infrared, or computervision-based sensors. Master control 10 may stream data in from one ormore different types of sensors located within the physical workcell.For instance, data from the sensors may reflect dimensions or otherproperties of parts and/or materials within a physical workcell, as wellas how the parts and/or materials are currently positioned within thereal world. This data may then be streamed out to one or more roboticdevice actors 42 and 44 within the environment to control roboticactions, such as to accurately define a pick-up point or to adjust thepressure applied to a particular material to avoid damaging thematerial.

In further examples, robotic device actor 42, 44 may be configurable tooperate one or more tools for use in construction, such as spindles,grippers, drills, pincers, or welding irons. In some examples, roboticdevice actors 42, 44 may be able to switch between one or more toolsduring a building process using a tool rack and/or automated toolchanger 50. For instance, master control 10 may contain programminglogic in order to automate the selection and equipping of tools fromtool rack 50. In other examples, instructions to cause one of therobotic device actors 42, 44 to change tools using the tool rack/toolchanger 50 may come from independent manual control 28 as well orinstead.

III. EXAMPLE SYSTEM DEVICES

Referring now to FIGS. 2A-2C and 3A-C, several non-limiting examples ofsystem devices 40, including robotic device actors 42, 44 and a toolrack/tool changer 50 will be described. Although these figures focus onthe use of robotic arms, other types of device actors 42, 44 or systemdevices 40 may be used in some examples as well or instead.

FIG. 2A illustrates a robotic device actor, according to an exampleembodiment. In particular, robotic device actor 200 may include arobotic arm 202 with an end effector 204 capable of being equipped withone or more different tools. The robotic arm 202 may be capable ofmotion along six degrees of freedom, depicted in FIG. 2A as A1-A6. Incertain examples, robotic device actor 200 may be further capable ofmotion along one or more axes A0, such as along a rail which is notshown that allows side to side movement. In certain embodiments,instructions may be given to position end effector 204 at a specificlocation, and the positions of the robotic arm 204 along A1-A6 and/or ofrobotic device actor 200 along one or more axes A0 may be calculated bya process of the related manufacture control system. In alternativeembodiments, position control of robotic device actor 200 and/or roboticarm 202 may require separate, individual settings and control commands.Robotic devices operating with fewer degrees of freedom may be used insome examples as well or instead.

FIG. 2B illustrates robotic device actor 200 equipped with a gripper206. In particular, the gripper 206 may be placed at end effector 204 ofthe robotic arm 202. The gripper 206 may be used for various functionsduring a building process, such as picking up objects or parts, movingobjects or parts, holding objects or parts, and/or placing objects orparts. A variety of different types of grippers may be used, such as avacuum gripper, a tumble gripper, or a passive centering gripper.Additionally, grippers with different dimensions or other properties maybe used, possibly to coincide with different types of robot actorswithin a physical workcell.

FIG. 2C illustrates robotic device actor 200 equipped with a spindle208. A spindle 208 may include a rotating axis for use in variousfunctions within a building process, such as cutting materials, shapingmaterials, milling or routing. The spindle 208 could be a variety ofdifferent types, such as a grinding spindle, an electric spindle, alow-speed spindle, or a high-speed spindle. Additionally, spindles withdifferent dimensions or other properties may be used, depending on thedifferent types of robot actors within a physical workcell. In someexamples, other types of tools may be used by robotic device actors aswell or instead.

FIG. 3A illustrates a tool rack, according to an example embodiment. Thetool rack may contain a number of different fabrication tools (e.g.,spindles or grippers) and may be used along with an automated toolchanger in order to equip robotic devices with particular tools to usewithin a physical workcell. In some examples, the tool rack may containseveral tool rack modules 302, 304, 306, 308 positioned along a track300, with each of the tool rack modules 302, 304, 306, 308 containingone or more particular tools. In some examples, one or more of the toolrack modules 302, 304, 306, 308 may be moveable along the track 300. Infurther examples, a tool rack module may be capable of interfacing witha slave module that allows for a particular tool to be selected from thetool rack module and then equipped onto a robotic device. For instance,referring to FIG. 3A, tool rack module 302 may interface with slavemodule 310 and tool rack module 306 may interface with slave module 312.

In order to facilitate tool changing, the tool rack modules may beequipped with built-in safety sensors to minimize the risk of accidentaltool fetch and drop commands. Additionally, the tool change slavemodules may include IO breakout boxes to simplify passing IO triggersignals to control tools. In some examples, the breakout boxes mayinterface with a timing control system, such as master control 10described with respect to FIG. 1, that controls the robotic deviceswithin a physical workcell. Master control 10 may be used to direct atool change for a particular robotic device, which may be configured inadvance using software control 26 and/or from independent manual control28 during runtime.

FIG. 3B illustrates use of the tool rack to equip robotic devices withtools, according to an example embodiment. In particular, a firstrobotic device 314 may move its end effector 316 to a position over aslave module 310 that interfaces with a tool rack module 302 of a toolrack. For instance, the robotic device 314 may currently be equippedwith gripper 318, and may be controlled to move to the tool rack inorder to place gripper 318 in the tool rack and equip a different toolheld by tool rack module 302. Additionally, a second robotic device 320may have positioned its end effector 322 on slave module 312 in order toequip spindle 324, which may have been held by slave module 312. Afterequipping spindle 324, robotic device 320 may then proceed to move awayfrom the tool rack and complete operations using the spindle 324. Thetool rack modules may be positioned on the tool rack so that multiplerobotic devices may equip or change tools at the same time. In someexamples, additional rack modules 304, 308 may contain additional toolsthat may be equipped by one or more robotic devices.

In further examples, instructions from a control system, such as mastercontrol 10 described with respect to FIG. 1, may be used in order toinstruct a robotic device how to equip a tool during runtime (e.g., todetermine where a tool is within the tool rack and solve an end effectorproblem in real time in order to position the end effector over a slavemodule to enable the robotic device to pick up the tool), hi additionalexamples, a drive system (e.g., a VFD used to supply power drive aspindle) may be mounted at a separate fixed location within a physicalworkcell in order to supply power on the tool changer system.

IV. EXAMPLE GRAPHICAL INTERFACES

FIG. 4A shows a graphical interface containing a 3D model, according toan example embodiment. As shown, a graphical interface 400 may containan input window 402 which may allow a user to enter parameters relatingto an output product 406, such as a wall built using individual sticks.The input window 402 may allow the user to enter parameters 404 that mayrelate to aspects of the output product, including dimensions, density,curvature properties, other geometric properties, materials to be used,and/or other numeric inputs. The inputs may be used to derive aparametric solution for an output product 406. Additionally, the inputsmay be used to generate a sketch of the output product 406 within adisplay window 408 of the graphical interface 400.

FIG. 4B shows three different output products based on different userinput parameters, according to an example embodiment. A first view ofthe graphical interface 440 may contain an input window 402 and adisplay window 408. The input window 402 may allow a user to enterparameters 404 relating to a desired output product, including productdimensions, density, curve offsets, amount or type of curvatures, and/orother geometric or numerical inputs. Based on the input parameters 404,a geometric representation of the output product 406 may be displayedwithin the display window 408. In some examples, a user may modifyindividual parameters 404 in order to change aspects of the outputproduct 406.

For instance, a second view of the graphical interface 450 shows adifferent output product 406 within the display window 408 based ondifferent input parameters 404 within the input window 402. In thisexample, dimensions of the output product 406 and/or materials used toproduce the output product 406 may be modified to produce an outputproduct 406 with a greater height as shown in the second view 450.Further, a third view 460 shows another different output product 406within the display window 408 based on different input parameters 404within the input window 402. For example, parameters relating to thecurvature of the output product may be modified by a user in order toproduce another different output product 406 as shown in the third view460.

FIG. 5 shows a graphical interface for architecting a robotic buildingprocess, according to an example embodiment. For example, the graphicalinterface may be part of software control 26 as described above withrespect to FIG. 1. As shown, a graphical interface 500 may contain aninput window 502 which allows a user to control aspects of the buildingprocess, including nodes related to robot actors, tools, motion paths,and tool operations for use during construction. The graphical interface500 may additionally contain a display window 510 which contains a 3Dgeometric view of the physical workcell, including components such asrobot actors, tools, materials, and/or constructed output products. Inexample embodiments, the input window 502 may provide a visualprogramming interface or different type of interface that may allow auser to enter parameters describing a desired output product and/orinformation about the actors and tools to be used in the buildingprocess. Input data collected using the input window 502 may be used tocontrol geometry and/or other aspects of the physical workcell displayedwithin the display window 510.

In one example, a user may input parameters to control a buildingprocess using an input window 502 containing a visual programminginterface, such as an interface built using a visual programminglanguage, such as a commercial software program known as Grasshopper.The interface may allow a user to include one or more nodes 504 whichmay represent components of the building process, such as robot nodesrepresenting different types and/or configurations of robots, tool nodesrepresenting different types and/or configurations of tools, IO nodesrepresenting types of available IO, track nodes representing possibletracks of motion of robot actors, and command nodes for determiningmotion commands and other types of commands for robot actors.

As shown within window 502 of FIG. 5, individuals nodes 504 may beconnected together using connectors 506. A connector 506 between twonodes may indicate that the output of a first node is to be used as aninput to a second node. For instance, a single robot node may receive asinputs information from several different component nodes, such as nodesrepresenting the type of robot, the type of tool used by the robot, atrack the robot can travel along, and so on.

In further examples, the window 502 of FIG. 5 may contain a timeline508. The timeline 508 may have a cursor representing a current timestamp(e.g., 83 as shown in the figure) which may represent a particular pointin time of the manufacturing process. In addition, the timeline 508 maycontain buttons to play through the building process at a particularspeed, or fast-forward or rewind through the building process. Thetimeline 508 may be used to control the point in time at which thegeometry and/or other aspects of the physical workcell are displayedwithin the display window 510. Further, the timeline 508 may be used toindicate a particular point in time either for purposes of simulatingthe building process or for visualizing within software an actualphysical building process taking place within the physical world.

As shown in FIG. 5, the user interface may additionally contain displaywindow 510 which may display geometry and/or other aspects of thephysical workcell based on inputs from the input window 502. Forexample, the display window 510 may include geometry relating to robotactors, tools, building materials, robotic motion paths, and outputproducts, among other things. In one example, the display window 510 maybe designed using a commercial 3D modeling software, such as Rhinoceros,as shown within FIG. 5. The display window 510 may display geometrywithin a particular physical workcell 512. The display window 510 mayinclude options to change the perspective of the physical workcell 512and/or to zoom in or zoom out a view of the physical workcell 512.

The physical workcell 512 may include one or more robot actors 514. Therobot actors 514 may be device actors 42 and/or 44 as described abovewith respect to FIG. 1 and/or robotic device 200 as described withrespect to FIGS. 2A-2C. Support may be provided for numerous differenttypes of multi-axis robotic systems of different types and/or fromdifferent manufacturers. In some examples, one or more of the robotactors 514 may be traditional six-axis robots. In additional examples,other types of robots that may be configured to operate along fewer ormore axes may be included for use within the physical workcell 512 inaddition or instead.

In further examples, robot actors may be represented within a softwareinterface as robot nodes, which may be put together from a number ofinterchangeable component nodes, including robot nodes representingdifferent makes and models of commercial robots, tool nodes representingdifferent types of physical tools that may be used for construction suchas grippers or spindles, IO nodes representing different types IOavailable to communicate with a robot actor and track nodes representingdifferent types of axes that a robot can move along. In some examples,individual tools and/or tooling parameters (such as wrist mount offsetsor tool center points) can be abstracted into components that can beassembled by a user into compound tools as well.

The display window 510 may additionally contain one or more motion paths516 representing paths of motion of individual robot actors 514. Themotion paths 516 may indicate paths to be taken by the robot actors 514during the building process, such as to pick up materials and attachthem to an object under construction. In some examples, the motion paths516 may further indicate points at which particular input or outputactions will occur. For instance, an “x” on a motion path 516 mayindicate a point at which a robot actor 514 uses a tool such as agripper to pick up a particular type of material. In further examples,the motion paths 516 may be synchronized with the timeline 508 from theinput window 502. Accordingly, in some examples, the robot actors 514may be made to move along the motion paths 516 to positions atparticular points in time based on the timestamp indicated by thetimeline 508.

The physical workcell 512 may additionally contain one or more materials518 to be used during the building process, in this simplified example,the materials 518 consist of sticks used to construct a wall 520. Motionpaths 516 may be determined for the robot actor 514 to take in order tomove the individual sticks 518 onto the wall 520. In other examples, avariety of different types of materials, including connective materialssuch as glue, may be used simultaneously by the robot actors toconstruct more complex output products.

In further examples, the physical workcell 512 may also contain othercomponents not shown in FIG. 5 that may be used in the building process.For instance, one or more sensors may be included to sense informationabout the robot actors and/or materials in the physical workcell inorder to influence motion paths taken by the robot actors. For example,a torque sensor may be used to determine if a particular piece ofmaterial is likely to break under stress. A control system, such asmaster control 10 described above with respect to FIG. 1, may be used tointerface with the robot actors and/or sensors within the physicalworkcell.

In some examples, the display window 510 may provide users with multiple3D views of the physical workcell, and may allow a user to change theorientation and/or zoom of a particular view. In other examples, thedisplay window 510 may present other types of representations of thephysical workcell, such as numerical representations, as well orinstead.

V. EXAMPLE SYSTEM WORKFLOW

In some examples, an input window may additionally contain a toolbarcontaining digital tools to control aspects of the building process.FIG. 6A shows a toolbar for a graphical interface, according to anexample embodiment. The toolbar 602 may be equipped with a variety ofdifferent toolsets 604 that may be used to design or control a buildingprocess within an input window of a graphical interface. Toolsets 604may be provided with digital toots relating to generating robot motionpaths, transforming between different planes or axes, describing robotactors, describing physical building tools, sequencing individual robotmotions, communicating data input and/or output to and/or from robotactors, mapping between a virtual software environment and a physicalworkcell, and/or enabling visualization of a building process, forexample.

FIG. 6B shows an organization of digital tools within a toolbar,according to an example embodiment. As shown, the digital toots may bedivided into a number of different categories. The digital tools maythen be used in combination to design a building process, as shown byFIG. 6C. FIG. 6C is a block diagram of an example workflow, according toan example embodiment. In particular, FIG. 6C shows workflow involving anumber of digital tools, which may be accessible within a toolbar asdepicted in FIG. 6A and FIG. 6B or by another means within a graphicalinterface. As shown, the digital tools may be divided into a number ofdifferent categories. One or more digital tools from a number ofdifferent categories may be selected by a user to affect particularaspects of the building process, including the robot actors and othercomponents within a physical workcell that may be used in the process.

In one example, a toolbar may include path tools 608 relating togenerating target planes that may be used to determine motion paths ofrobot actors. In some examples, the path tools 608 may take as inputgeometry 606 describing a desired output product, such as geometrygenerated by parametric modeling software, Grasshopper. For instance,the output product geometry 606 may be generated based on user inputwithin an input window specifying aspects of the output geometryincluding dimensions, density, curvature, materials, and so on. The pathtools 608 may then determine target planes for robot motion paths basedon the output product geometry 606.

In some examples, the output product geometry 606 may include particularsplines, surfaces, and/or other geometrical constructions to be includedwithin an output product. The path tools 608 may then provide shortcutsfor generating target planes relating to aspects of the output productin a format that can be turned into particular robot trajectories thatmay be used to construct an output product containing the target planes.Motion paths fir individual robot actors may then be derived as afunction of the target planes in addition to tool definitions andmaterial properties, for example.

In further examples, a toolbar may include transform tools 610 relatingto transformations between different axis frames or offsets, as shown byFIG. 6B and FIG. 6C. For instance, the transform tools 610 may providetransformations between coordinate frames at the base or joints of aparticular robot and a stage containing the output product. In otherexamples, the transform tools 610 may additionally allow fortransformations between multiple robots operating within differentframes of reference as well. As shown in FIG. 6C, transformations may beapplied before and/or after determining sequences of motion forindividual robot actors.

In further examples, a toolbar may include stage tools 612 thatrepresent aspects of a physical workcell, such as robot actors, tools,IO, and/or axes. In some examples, stage tools 612 may also provide amapping between virtual robots in software and physical robot actorswithin the physical workcell, as shown by FIG. 6B and FIG. 6C. The stagetools 612 may be used by engine node 624 to send trajectories for robotactors to take based on output from command tools 622 to a controlsystem 628. In some examples, stage node 612 may be configured in orderto specify the currently available robotic devices and/or tools within aparticular physical workcell. The control system 626 may then commandrobot actors and/or other components within the physical world 630 basedon information from stage tools 612.

In some examples, stage tools 612 may take input from one or more robotnodes 614 representing attributes of individual robot actors within aphysical workcell, as shown by FIG. 6B and FIG. 6C. A robot node 614 maybe used to define attributes of a robot actor, such as traditionalsix-axis robots or other types of robots. The robot attributes mayinclude link lengths of the robot and/or arm lengths of the robot,offsets of the robot and/or joints of the robot, and/or limits on robotjoint movement or maximum torque that a robot joint can handle, forexample.

In additional examples, stage tools 612 may also take input from one ormore tool nodes 616 for defining the attributes of physical buildingtools and/or a tool rack for holding the tools, as shown by FIG. 6B andFIG. 6C. For example, attributes of building tools such as grippers orspindles may be specified by tool nodes, which may be used to configurean automatic tool changer so that robot actors can easily switch betweentools. In some examples, robot actors may switch between tools using atool rack which stores the tools and facilitates a tool changingprocess, as described above with respect to FIGS. 3A and 3B.

In further examples, the tool nodes 616 may include support for compoundtooling that may allow component tools to be assembled into compoundtools. In particular, individual tooling parameters (e.g., wrist mountoffsets or tool center points) may be abstracted into components thatmay be assembled into compound tools. For instance, multiple tools maybe aggregated into one compound tool that has multiple tool orientationsand/or center points that may be used depending on which component ofthe tool may be required at a particular time. For example, a compoundtool with an automatic tool changer may be represented by a masterinterface plus a number of different attachments, such as a spindle, avacuum array, or a gripper. In another example, a compound tool mayinclude a series of different tools, such as a gripper plus a tensionerplus a roller. Other examples of combining multiple tools and/orcombining tools by abstracting tooling into parameters that define toolorientation and/or center points are also possible.

In further examples, stage tools 612 may also take input from one ormore IO nodes 618. The IO nodes 618 may describe information relating todigital and/or analog input and/or output actions that may be taken by arobot actor, such as the type of action (e.g., gripping a material) andattributes associated with the action (e.g., width of material that canbe gripped). In additional examples, the robot attributes may includeone or more axis nodes 620. The axis nodes 620 may describe one or morelinear and/or rotational axes along which a robot can travel, includinglimitations on the robot's movements along the axes.

In additional examples, a toolbar may include command tools 622, asshown by FIGS. 6B and 6C. The command tools 622 may be used to determinerobot commands to cause one or more of the robot actors to executeparticular operations, which may include point-to-point motions, motionsalong external axes, and/or input or output events. For example, one ofcommand tools 622 may be used to direct a particular robot motion alongone of six degrees of freedom, a particular robot motion along anexternal axis, or a particular input or output event, such as applyingglue to a material in a particular manner. Additionally, command tools622 may be included for creating step nodes that instruct robot actorsto take a particular sequence motion steps and carry out one or moretool actions. In further examples, coordinated sequences of motions maybe generated for multiple robot actors working together within a singletimeframe.

In some examples, step nodes, or sequences of motions and actions, canbe abstracted into reusable subroutines. For instance, a subroutine canbe defined by connecting visual building blocks, which may representparticular motion commands or motion parameters. The subroutine couldthen be used to make one or more robots carry out the same actionsequence multiple times within a single building process. In someexamples, steps can be synchronized across multiple robots so thatmultiple robots can work in a shared environment simultaneously. Examplesystems may also include an engine node 624, which may assign each ofthe steps to particular robotic devices within a stage.

In further examples, users may be provided with functionality to switchbetween steps within the graphical interface. For instance, timeline 508as illustrated and described with respect to FIG. 5 may also includesbuttons to skip between steps on the timeline. In some examples, digitalbookmarks may be inserted by a user for particular steps. For instance,through the graphical interface, it may be possible to jump from thebeginning of a “fetch stick” step to the beginning of a “nail stick”step. These bookmarks steps within the timeline may match the stepsauthored by the user by inputting motion commands, IO commands, and/orother commands in a step node.

Additionally, the engine node 624 may communicate with control system626. The control system 626 may be a computing device capable ofcommunicating wirelessly with robot actors and/or other components suchas sensors within the physical workcell in the physical world 630. Inparticular, the control system 626 may provide access to real time datastreams from all robot actors and devices, which may allow for precisecontrol over the physical workcell at particular points in time. Thecontrol system could communicate with some or all of the actors ordevices through wired connections or other types of communicationchannels as well or instead, including previously described networkprotocols.

In some examples, the control system may additionally contain a physicalcontrol interface such as a touchscreen interface that may allow a userto interact with the control system to view live data or modify robotactions in real time. For instance, a stage file containing informationabout the physical workcell including actors, tools, materials, andenvironmental setup on the control system 626 may be accessible via aprogramming interface. A user who is watching a building process withinthe physical world 630 may then make modifications to the process beforeit is completed.

In additional examples, a toolbar may include data input/output toots628 that may allow the control system 626 to send and/or receive data toand/or from the virtual software environment that determines robotmotion paths, as shown by FIG. 6B and FIG. 6C. Accordingly; telemetryfrom the control system 626 may be used to create a live link betweenthe virtual world in software and the physical world 630. For instance,the data input/output tools 628 may be used to process information fromthe control system 626 relating to the robot actors within the physicalworkcell and/or other components in the workcell such as sensors. Basedon this information about the physical world 630, the virtual robotswithin software may be updated with real-time feedback from the physicalworld 630 (e.g., motion paths for robot actors may be determined ormodified based on real-time sensor data).

Additionally, the data input/output tools 628 may be used to send databack to the control system 626 so that the control system 626 caneffectuate particular input or output actions within the physical world630, for example. For instance, the control system 626 may instruct arobot actor how use a tool in the physical world 630 (e.g., how tocontrol a spindle) based on information from one or more digital toolswithin the software interface.

In further examples, engine node 624 include visualizer or simulationtools that may allow a user to simulate a building process through auser interface in software, as shown by FIG. 6B and FIG. 6C. In someexamples, the visualizer tools may display the building process asgeometry drawn on a screen that shows the physical workcell. In otherexamples, the visualizer tools may display the building process ascurves representing particular data values as well or instead.Additionally, in further examples, the visualizer tools may also be usedto visualize a building process in software as it is actually occurringwithin the physical world 630. In some examples, the visualizer toolsmay additionally provide a graphical representation of potentialconflicts within a particular building process, such as when a robot'smotion path extends outside its possible range of motion or when tworobot actors may be going to collide based on the currently definedtrajectories and/or step sequences.

In further examples, the visualizer component may allow a user to seesimulations of the building process in advance and/or as the buildingtakes place. In some examples, the user may use the visualizer componentoffline to see robotic motion paths as well as input/output events overa series of sequential steps as geometry drawn within a viewing window.In other examples, the user may be able to visualize a simulatedplayback as numerical data streams relating to the robot actors,materials, and/or other aspects of the physical workcell representedthrough curves in addition to or instead of visual geometry. In furtherexamples, the user may also be able to see particular data points atindividual timesteps, such as robotic joint values, axis values, orinput/output values.

In some example systems, a user may also be able to use the visualizercomponent to visualize a building process that is occurring in thephysical world in real time. The system may interface with a controlsystem that receives real-time data streams from sensors that may beused to scan the physical workcell, individual robot actors, and/orparts used in construction as an output product is being built.Accordingly, the visualizer's user interfaces may be updated in realtime to reflect real world dimensions, properties, and/or positions ofobjects and actors within the environment.

VI. EXAMPLE METHODS

A method 700 is provided for instructing robotic devices to operate in atime-based mode within a workcell, according to an example embodiment.In some examples, method 700 may be carried out by a control system,such as manufacture control system 100, master control 10, and/orsoftware control 26 as described in reference to FIG. 1. The controlsystem may communicate with the robot actors using any of the networkprotocols or communication methods previously described. In additionalexamples, part or all of method 700 may be executed by any of thegraphical interfaces or systems described and illustrated with respectto FIGS. 4A-4B, 5, and 6A-6C. In further examples, part or all of method700 may be carried out by one or more robotic devices, such as deviceactors 42, 44 within system devices 40 as described in reference to FIG.1, or device actor 200 as illustrated and described in reference toFIGS. 2A-2C. Additionally, while examples with certain numbers and typesof system devices may be described, various alternative embodiments mayinclude any number and type of robotic devices as well.

Furthermore, it is noted that the functionality described in connectionwith the flowcharts described herein can be implemented asspecial-function and/or configured general-function hardware modules,portions of program code executed by a processor for achieving specificlogical functions, determinations, and/or steps described in connectionwith the flowchart shown in FIG. 7. Where used, program code can bestored on any type of computer-readable medium, for example, such as astorage device including a disk or hard drive.

In addition, each block of the flowchart shown in FIG. 7 may representcircuitry that is wired to perform the specific logical functions in theprocess. Unless specifically indicated, functions in the flowchart shownin FIG. 7 may be executed out of order from that shown or discussed,including substantially concurrent execution of separately describedfunctions, or even in reverse order in some examples, depending on thefunctionality involved, so long as the overall functionality of thedescribed method is maintained.

As shown by block 702 of FIG. 7, method 700 may include receivingordered sequences of operations for a plurality of robotic devices. Inparticular, an ordered sequence of operations may be determined for eachrobot actor within a workcell. An ordered sequence of operations for aparticular robot may include a sequence of target positions for an endeffector of the robot to move through some examples, other types ofoperations may be interspersed between the motion commands that causethe robot to move between target positions. For example, tool actionsmay be defined for a robot to activate a physical tool at particularpoints within its motion paths during a manufacturing process.

In some examples, the ordered sequences of operations for the roboticdevices may be generated by a software authoring environment, such assoftware control 26 as described in reference to FIG. 1. In particular,a user may use a software interface to define sequences of operationsfor one or more robots to collectively complete a manufacturing orconstruction process. For example, motion paths and tool actions may bedefined for two or three or four robot actors within a workcell in orderto construct a physical output product. In further examples, sequencesof operations for one or more of the robotic devices may have beendefined previously and saved within memory or a computer-readablemedium. In some examples, sequences of operations for different roboticdevices to perform different parts of a manufacturing process may becreated at different times and then combined at a later time forsimultaneous execution.

FIG. 8A illustrates an example of sequential robotic operation,according to an example embodiment. More specifically, a robot actor 802is shown within a workcell used for manufacturing processes. The robotactor 802 could be any of the types of robotic devices previouslydescribed. Here, robot actor 802 is equipped with a gripper 804, butother types of tools could be used by robot actor 802 as well orinstead. Sequences of operations may be provided for the robot actor 802to pick up sticks from a pile of sticks 806 and place the sticks onto astick wall 808 under construction. It should be understood that thescenarios shown here are for illustration purposes and any number ofother different types of materials and output products may be usedinstead.

A sequence of operations for robot actor 802 may include a sequence oftarget positions 810, 812, 814 for the robot actor 802 to move through(or to move gripper 804 through). The target positions 810, 812, 814 maybe translational and rotational positions within the workcell (e.g.,with 6 degrees of freedom). In some examples, fewer degrees of freedommay be used for certain robot actors, depending on the robot actor'smotion capabilities. In further examples, when operating in sequentialmode, robot actor 802 may mow between consecutive target positions withstraight lines by default. For example, robot actor 802 may follow path816 to move between target position 810 and target position 812, andthen may follow path 818 to move between target position 812 and targetposition 814. In additional examples, tool actions may be includedwithin sequences of operations for robot actor 802. For example, a toolaction to activate gripper 804 pick up a stick at target position 812and a second tool action to release gripper 804 to drop the stick attarget position 814 may be included within the sequence of operationsfor robot actor 802.

In further examples, the number of target positions defining motionpaths for robot actors may vary within different sequences ofoperations. For example, additional target positions may be provided tofurther refine path 816 and path 818 in some examples. In some examples,different granularity may be used for different sequences of operationsfor robot actors within a workcell as well, possibly depending on thetypes of tasks assigned to each robot actor.

Method 700 may additionally include determining time-based sequences ofoperations for each of the robotic devices, as shown by block 704. Morespecifically, a time-based sequence of operations for a particularrobotic device may indicate positions of the robotic device and/or anend effector of the robotic device at corresponding timesteps of aglobal timeline. The positions within the time-based sequence ofoperations may include the target positions from the ordered sequence ofoperations for the corresponding robotic device that was received inblock 702. In some examples, other types of robot operations may beincluded within the time-based sequence of operations from thecorresponding received sequence of operations as well. For example, ifthe sequence of operations caused a robotic device to perform part of aconstruction process using a tool, the time-based sequence of operationsmay additionally contain tool actions for the robotic device to activatethe tool at particular timesteps of the global timeline as well.

In further examples, a particular time interval may separate consecutivetimesteps in each of the time-based sequences of operations. Forinstance, positions for each of the robotic devices within a workcellmay be determined at each timestep (e.g., every 12 milliseconds). Insome examples, the interval used may depend on the communication ornetwork capabilities of control systems, such as master control 10described with respect to FIG. 1, and/or the computing abilities ofsystem devices 40 or corresponding device controllers. In furtherexamples, a control system such as master control 10 may be used toprovide instructions to controllers on the robotic devices to positionthe robotic devices at each timestep. In some examples, a time intervalbetween 10 milliseconds and 20 milliseconds may be used. Other timeintervals may be used in different examples as well.

FIG. 8B illustrates an example of time-based robotic operation,according to an example embodiment. More specifically, the sequence ofoperations including target positions 810, 812, and 814 may be used todetermine a time-based sequence of operations for robot actor 802 tomove gripper 804 through. The dashes on motion path 820 and motion path822 may represent the position of gripper 804 (or the end effector ofrobot actor 802) at timesteps along a global timeline. For example, if atime interval of 12 milliseconds is used in determining the time-basedsequences of operations for robot actor 802, then consecutive dashesalong motion path 820 and motion path 822 may represent the change inposition of gripper 804 during a particular 12-millisecond section ofthe global timeline.

In some examples, additional positions for the robotic device may beinserted within the time-based sequence of operations between targetpositions from the received sequential operations. For example, aparticular sequence of operations received in block 702 for a robotactor may only contain positions that the robot actor can reach everysecond or every ten seconds or every minute. However, the time intervalused to determine the time-based sequence of operations (e.g., 10milliseconds or 20 milliseconds or 100 milliseconds) may allow for manymore positions to be defined, which may allow for more precise controlof a robot's motions. In further examples, different time intervals maybe used for different robotic devices as well, possibly depending on thecapabilities of hardware or controllers of the different devices.

Referring again to FIG. 8B, positions may be inserted within thetime-based sequence of operations for robot actor 802 between targetpositions 810 and 812 along motion path 820. In some examples, thepositions may be chosen to minimize the amount of time spent by robotactor 802 in moving from target position 810 to target position 812. Forinstance, the positions at each time step may be solved for by solvingan optimization problem to minimize the total time usage. In furtherexamples, velocity and/or acceleration curves of robot actor 802 alongmotion path 820 may be optimized in determining the time-based sequenceof operations for a robot actor as well or instead. For instance,maximum velocity curves relative to the global timeline may bedetermined for each robot actor in an effort to minimize total timeusage during a manufacturing process. For example, in FIG. 8B, thevelocity of gripper 804 may be maximized in between target positions andthen reduced as a target position is approached in order to stop thegripper 804 at the target position.

In additional examples, the positions may be determined in order tominimize the amount of power used by robot actor 802 in moving fromtarget position 810 to target position 812. For example, fluid motioncurves may be used instead of rigid point-to-point motions to reduceenergy consumption. In further examples, fluid motion curves may also beused to cause a robotic device to simulate physical phenomena moreprecisely. For instance, a robotic device controlled to replicate theflight of a quadcopter, or a roller coaster ride, or the forces ofhitting a surface made of various different materials in order to testthe performance of a particular object may all benefit from a moreprecise time-based description of trajectory.

Method 700 may additionally include determining one or more potentialcollisions that would result from parallel execution, as shown by block706. More specifically, the time-based sequences of operations for twoor more robotic devices within a workcell may be synchronized to acommon clock. The positions of the robotic devices at timesteps alongthe global timeline may then be used to determine when collisions mayresult between robotic devices. Possible collisions may includecollisions involving two of the robotic devices themselves, collisionsinvolving one or more tools used by the robotic devices, and/orcollisions involving materials or products being moved or operated on byone or more of the robotic devices. By using a smaller time intervalbetween consecutive positions for each of the robotic devices along theglobal timeline, collision detection may be performed with greaterconfidence.

In further examples, one or more possible collisions may be determinedduring parallel operation of the robotic devices. For example, due tocalibration inaccuracy or unexpected effects from manufacturingoperations, the precise position of robotic devices and/or othercomponents within a workcell may not be known until a manufacturingprocess has started. In such examples, certain possible collisions maybe identified and avoided on the fly. In further examples, thetime-based sequences of operations for the robotic devices may bedetermined in stages, with some operations determined during execution.For instance, sequential operations may be used to determine time-basedsequences of operations for the robots to execute during the first fiveminutes of the global timeline. Then, after executing some or all of theoperations, another five-minute block of operations may be determined.Determining sequences of operations and/or predicted collisions may beperformed at other times or in other combinations in some examples aswell.

FIG. 8C illustrates motion paths of two robotic devices operating inparallel, according to an example embodiment. More specifically,time-based sequences of operations may be determined for robot actor 802and robot actor 824 to perform in parallel within a workcell. Robotactor 802 may be equipped with a gripper 804, and robot actor 824 may beequipped with a spindle 826 for use during a manufacturing process.Motion paths 820 and 822 may be determined for robot actor 802 in orderto cause robot actor 802 to move its gripper 804 to pick up a stick froma pile of sticks 806 and then place the stick on a stick wall 808.Additionally, motion path 834 may be determined for robot actor 824 tosimultaneously move its spindle 826 from a first target position 830 toa second target position 832 located at a box of materials 828. Forinstance, robot actor 824 may be assigned to pick up screws from a boxof screws 828 in order to insert screws into sticks on stick wall 808.

The motion paths 820, 822 for robot actor 802 and the motion path 834for robot actor 824 may be synchronized to a common clock. Morespecifically, the dashes along motion paths for each robot actor mayrepresent positions of the robots at timesteps along global timelines.By comparing the positions of each robot actor at particular timesteps,possible collisions between robot actors may be predicted. For example,a possible collision between robot actor 802 and robot actor 824 may bepredicted at 836. In some examples, possible collisions may includepoints at which robotic devices come within a distance of each otherthat is less than a predetermined safety buffer. For instance, a safetybuffer may be used to avoid collisions resulting from imprecision incalibration and/or commanded robot positions.

Method 700 may additionally include modifying at least one of thetime-based sequences of operations in order to prevent the identifiedcollisions, as shown by block 708. More specifically, a time-basedsequence of operations may be modified by modifying timestepscorresponding to particular operations and/or by inserting, removing, ormodifying particular operations within the sequence. In some examples,the time-based sequences of operations may be modified in an effort tominimize the total time required to complete a manufacturing process, orthe additional amount of time resulting from ensuring that no collisionsresult during parallel execution. In further examples, modifications maybe determined to minimize usage of other resources (e.g., energy orpower) in addition or instead.

In some examples, the rate of operation of one or more of the roboticdevices may be modified in order to avoid a collision. For example,referring to FIG. 8D, the rate of operation of robot actor 802 may beslowed down in moving from target position 812 to 814. In particular,the distance between the position of gripper 804 between consecutivetimestamps may be reduced, as represented by the shortened distancebetween dashes along motion path 822. Robot actor 802 may be slowed downin order to ensure that robot actor 824 successfully crosses from targetposition 830 to 832 without colliding with robot actor 802.

In further examples, robot actors may be controlled to operate withdifferent speeds at different points along the global timeline. In someexamples, a velocity curve relative to the global timeline representingthe speed of movement or operation of a robotic device at each point intime along the timeline may be determined for each robotic device.Additionally, the velocity curves may be determined that maximize thevelocity or rate of operation of each of the devices while avoidingcollision. In other examples, velocity and/or acceleration curves may bedetermined to maximize the combined operating rate of all of the deviceswhen operating in parallel. For instance, the velocity curve of a robotactor whose construction operations take the longest time (and thuslimit the time to complete the entire process) may be maximized beforedetermining velocity curves for other robot actors.

In further examples, one or more operations may be inserted into one ormore of the time-based sequences of operations to cause one or morerobot actors to hold position for certain periods of time along theglobal timeline. In particular, instead of or in addition to modifyingthe rate of operation of one or more robots at one or more points,robots may be commanded to hold position for certain subsections of theglobal timeline. Referring to FIG. 8E, robot actor 802 may be commandedto hold position at a certain point 838 for one or more timesteps toallow robot actor 824 to pass. As shown in FIG. 8E, the rate ofoperation of robot actor 802 along motion paths 820 and 822 may not bemodified as in FIG. 8D, but a collision may still be avoided bycontrolling robot actor 804 to hold position at position 838. Inadditional examples, the option to cause robotic devices to holdposition at certain points in time and space may also be considered whendetermining position, velocity, and/or acceleration curves for therobotic devices to minimize time usage and/or usage of other resourcesas previously discussed.

In further examples, modifying the time-based sequences of operationsmay include modifying one or more positions between consecutive targetpositions in one or more of the time-based sequences as well or instead.For instance, a collision may be avoided between two robotic devices bymodifying the motion paths between target positions for one or both ofthe devices, such as motion path 820, 822, and/or 834 as described withrespect to FIG. 8C. In further examples, modifications to positions maybe performed in conjunction with any of the timing modificationspreviously discussed in order to prevent collisions, possibly whileoptimizing across time and/or other resources.

In additional examples, the sequences of operations received for roboticdevices at block 702 of method 700 may include one or more sync points.A sync point may correspond to an operation within the sequence ofoperations for each robot, and indicate a point that each robot mustreach before any of the robots are permitted to continue executingoperations. Instructions for industrial robots such as those used inmanufacturing processes may often include sync points to ensure that nocollisions or other types of interference occur from simultaneousoperation by multiple robots within a workcell. In some examples,inefficiencies may result from synch points that require one or morerobots to stop and wait for other robots to complete operations withinthe workcell.

In some examples, a process involving multiple robots and sync points,such as a manufacturing process, can be completed more efficiently whenconverting to time-based mode. In particular, by performing collisionchecking at timesteps along the global timeline, some or all of the syncpoints may be disregarded. Robotic devices may be allowed to continueoperation rather than stopping at a sync point, and collisions may beavoided by modifying time-based sequences of operations using any of themethods previously discussed. In some examples, collisions may beavoided more efficiently (in time or a different resource) by solving anoptimization problem to determine position, velocity, and/oracceleration curves for the robotic devices rather than requiring stricthandshakes at sync points before any robot can continue.

In further examples, some sync points may be preserved when convertingto time-based mode. In particular, one or more of the sync points may beidentified as anchor points requiring synchronization between two ormore robotic devices in time-based mode. In some examples, anchor pointsmay correspond to sync points requiring synchronization for a purposeother than collision avoidance. In further examples, anchor points maycorresponding to sync points at which two or more robotic devices arecontrolled to operate on a single component within the workcell. Forinstance, during a construction process, a first robotic device may beassigned to hold a board while a second robotic device drives a nailthrough the board. In such an example, synchronization may be preservedto cause the first robotic device to continue holding the board untilthe second robotic device finishes nailing the board. In furtherexamples, other synch points which are not identified as anchor pointsmay be disregarded when converting to time-based mode, allowingtime-based sequences of operations crossing those points to be fluid andoptimized as previously discussed.

Method 700 may additionally include providing instructions for parallelexecution of the modified time-based sequences of operations by therobotic devices within the workcell, as shown by block 710. Inparticular, the time-based sequences of operations for each roboticdevice as modified to avoid collisions may be synchronized to a singleglobal timeline for execution, in some examples, a control system suchas master control 10 as described with respect to FIG. 1 may be used topush the time-based sequences of instructions onto controllers forindividual robotic devices for parallel execution (e.g., of amanufacturing process).

In further examples, the time-based sequences of instructions may bedetermined and/or provided to the robot controllers in blocks or stages(e.g., portions of the timeline). In yet further examples, time-basedsequences of instructions may be transmitted to robotic devices and/orcontrollers for robotic devices using any of the networking orcommunication methods previously described. In additional examples, someor all of the time-based sequences of operations may be determined andsaved (e.g., to a memory or computer-readable medium) for laterexecution. In further examples, only certain portions of sequences ofrobot operations may be provided for time-based parallel execution whileother portions are provided for sequential execution instead.

VII. CONCLUSION

The present disclosure is not to be limited in terms of the particularembodiments described in this application, which are intended asillustrations of various aspects. Many modifications and variations canbe made without departing from its spirit and scope, as will be apparentto those skilled in the art. Functionally equivalent methods andapparatuses within the scope of the disclosure, in addition to thoseenumerated herein, will be apparent to those skilled in the art from theforegoing descriptions. Such modifications and variations are intendedto fall within the scope of the appended claims.

The above detailed description describes various features and functionsof the disclosed systems, devices, and methods with reference to theaccompanying figures. In the figures, similar symbols typically identifysimilar components, unless context dictates otherwise, the exampleembodiments described herein and in the figures are not meant to belimiting. Other embodiments can be utilized, and other changes can bemade, without departing from the spirit or scope of the subject matterpresented herein. It will be readily understood that the aspects of thepresent disclosure, as generally described herein, and illustrated inthe figures, can be arranged, substituted, combined, separated, anddesigned in a wide variety of different configurations, all of which areexplicitly contemplated herein.

With respect to any or all of the ladder diagrams, scenarios, and flowcharts in the figures and as discussed herein, each block and/orcommunication may represent a processing of information and/or atransmission of information in accordance with example embodiments.Alternative embodiments are included within the scope of these exampleembodiments. In these alternative embodiments, for example, functionsdescribed as blocks, transmissions, communications, requests, responses,and/or messages may be executed out of order from that shown ordiscussed, including substantially concurrent or in reverse order,depending on the functionality involved. Further, more or fewer blocksand/or functions may be used with any of the ladder diagrams, scenarios,and flow charts discussed herein, and these ladder diagrams, scenarios,and flow charts may be combined with one another, in part or in whole.

A block that represents a processing of information may correspond tocircuitry that can be configured to perform the specific logicalfunctions of a herein-described method or technique. Alternatively oradditionally, a block that represents a processing of information maycorrespond to a module, a segment, or a portion of program code(including related data). The program code may include one or moreinstructions executable by a processor for implementing specific logicalfunctions or actions in the method or technique. The program code and/orrelated data may be stored on any type of computer readable medium suchas a storage device including a disk or hard drive or other storagemedium.

The computer readable medium may also include non-transitory computerreadable media such as computer-readable media that stores data forshort periods of time like register memory, processor cache, and randomaccess memory (RAM). The computer readable media may also includenon-transitory computer readable media that stores program code and/ordata for longer periods of time, such as secondary or persistent longterm storage, like read only memory (ROM), optical or magnetic disks,compact-disc read only memory (CD-ROM), for example. The computerreadable media may also be any other volatile or non-volatile storagesystems. A computer readable medium may be considered a computerreadable storage medium, for example, or a tangible storage device.

Moreover, a block that represents one or more information transmissionsmay correspond to information transmissions between software and/orhardware modules in the same physical device. However, other informationtransmissions may be between software modules and/or hardware modules indifferent physical devices.

The particular arrangements shown in the figures should not be viewed aslimiting. It should be understood that other embodiments can includemore or less of each element shown in a given figure. Further, some ofthe illustrated elements can be combined or omitted. Yet further, anexample embodiment can include elements that are not illustrated in thefigures.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopeand spirit being indicated by the following claims.

What is claimed is:
 1. A computer-implemented method comprising:receiving ordered sequences of operations for a plurality ofcorresponding robotic devices, wherein an ordered sequence of operationscomprises an ordered sequence of target positions within a workcell;determining, by a computing device, time-based sequences of operationsfor each of the plurality of corresponding robotic devices, wherein eachof the time-based sequences of operations indicates positions of thecorresponding robotic device within the workcell at correspondingtimesteps of a global timeline, and wherein the positions of thecorresponding robotic device within each of the time-based sequences ofoperations comprise the target positions from the ordered sequences ofoperations for the corresponding robotic device; determining one or morepotential collisions involving the robotic devices that would resultfrom parallel execution of the time-based sequences of operations withinthe workcell; modifying the time-based sequences of operations in orderto prevent the one or more potential collisions; and providinginstructions to cause parallel execution of the modified time-basedsequences of operations at timesteps of the global timeline by therobotic devices within the workcell.
 2. The method of claim 1, wherein aparticular time interval separates consecutive timesteps of the globaltimeline.
 3. The method of claim 1, wherein the target positions withinan ordered sequence of operations comprise positions of an end effectorof the corresponding robotic device, wherein the positions of the endeffector include six degrees of freedom.
 4. The method of claim 1,wherein determining the time-based sequences of operations for each ofthe plurality of corresponding robotic devices comprises determining,for each of the time-based sequences of operations, positions betweenconsecutive target positions of the corresponding robotic device thatminimize an amount of time between timesteps corresponding to theconsecutive target positions of the corresponding robotic device.
 5. Themethod of claim 1, wherein modifying the time-based sequences ofoperations in order to prevent the one or more potential collisionscomprises modifying one or more corresponding timesteps of one or morepositions within one or more of the time-based sequences of operations.6. The method of claim 5, further comprising: inserting operations tocause a certain one of the robotic devices to hold position at aparticular position for a subsection of the global timeline; andincreasing one or more corresponding timesteps of one or more positionsof the certain robotic device occurring after the particular position byan amount of time corresponding to a length of the subsection of theglobal timeline.
 7. The method of claim 5, wherein modifying the one ormore corresponding timesteps of the one or more positions within the oneor more of the time-based sequences of operations comprises determining,for each of the robotic devices, a maximum velocity curve at timestepsof the global timeline that does not result in a collision involving twoor more of the robotic devices.
 8. The method of claim 1, whereinmodifying the time-based sequences of operations in order to prevent theone or more potential collisions comprises modifying one or morepositions between consecutive target positions within one or more of thetime-based sequences of operations.
 9. The method of claim 1, whereinthe received ordered sequences of operations comprise one or more syncpoints, wherein a sync point corresponds to an operation within each ofthe ordered sequences of operations and indicates to cause each of therobotic devices to hold position at an operation corresponding to thesync point until each of the robotic devices reaches an operationcorresponding to the sync point; and wherein the method furthercomprises: determining one or more anchor points, wherein the one ormore anchor points comprise a subset of the one or more sync points; anddetermining the time-based sequences of operations so as to cause one ormore of the robotic devices to hold position at an operationcorresponding to an anchor point until one or more other robotic devicesreach an operation corresponding to the anchor point.
 10. The method ofclaim 9, wherein the one or more anchor points correspond to operationsfor two or more of the robotic devices to operate on a single componentwithin the workcell.
 11. The method of claim 1, wherein modifying thetime-based sequences of operations in order to prevent the one or morepotential collisions comprises modifying positions for one or more ofthe time-based sequences of operations between consecutive targetpositions to minimize an amount of time required to carry out theordered sequences of operations.
 12. The method of claim 1, whereinmodifying the time-based sequences of operations in order to prevent theone or more potential collisions comprises modifying positions for oneor more of the time-based sequences of operations to minimize an amountof power used by the robotic devices.
 13. A system comprising: anon-transitory computer-readable medium; and program instructions storedon the non-transitory computer-readable medium and executable by atleast one processor to: receive ordered sequences of operations for aplurality of corresponding robotic devices, wherein an ordered sequenceof operations comprises an ordered sequence of target positions within aworkcell; determine time-based sequences of operations for each of theplurality of corresponding robotic devices, wherein each of thetime-based sequences of operations indicates positions of thecorresponding robotic device within the workcell at correspondingtimesteps of a global timeline, and wherein the positions of thecorresponding robotic device within each of the time-based sequences ofoperations comprise the target positions from the ordered sequences ofoperations for the corresponding robotic device; determine one or morepotential collisions involving the robotic devices that would resultfrom parallel execution of the time-based sequences of operations withinthe workcell; modify the time-based sequences of operations in order toprevent the one or more potential collisions; and provide instructionsto cause parallel execution of the modified time-based sequences ofoperations at timesteps of the global timeline by the robotic deviceswithin the workcell.
 14. The system of claim 13, wherein a particulartime interval separates consecutive timesteps of the global timeline.15. The system of claim 14, wherein the particular time interval isbetween 10 milliseconds and 20 milliseconds.
 16. The system of claim 13,wherein the program instructions are executable by the at least oneprocessor to determine the time-based sequences of operations for eachof the plurality of corresponding robotic devices by determining, foreach of the time-based sequences of operations, positions betweenconsecutive target positions of the corresponding robotic device thatminimize an amount of time between timesteps corresponding to theconsecutive target positions of the corresponding robotic device. 17.The system of claim 13, wherein the program instructions are executableby the at least one processor to determine the time-based sequences ofoperations for each of the plurality of corresponding robotic devices bydetermining, for each of the time-based sequences of operations,positions that minimize an amount of power used by the robotic devices.18. The system of claim 13, wherein the program instructions areexecutable by the at least one processor to modify the time-basedsequences of operations in order to prevent the one or more potentialcollisions by modifying one or more corresponding timesteps of one ormore positions within one or more of the time-based sequences ofoperations.
 19. A non-transitory computer readable medium having storedtherein instructions, that when executed by a computing system, causethe computing system to perform functions comprising: receiving orderedsequences of operations for a plurality of corresponding roboticdevices, wherein an ordered sequence of operations comprises an orderedsequence of target positions within a workcell; determining time-basedsequences of operations for each of the plurality of correspondingrobotic devices, wherein each of the time-based sequences of operationsindicates positions of the corresponding robotic device within theworkcell at corresponding timesteps of a global timeline, and whereinthe positions of the corresponding robotic device within each of thetime-based sequences of operations comprise the target positions fromthe ordered sequences of operations for the corresponding roboticdevice; determining one or more potential collisions involving therobotic devices that would result from parallel execution of thetime-based sequences of operations within the workcell; modifying thetime-based sequences of operations in order to prevent the one or morepotential collisions; and providing instructions to cause parallelexecution of the modified time-based sequences of operations attimesteps of the global timeline by the robotic devices within theworkcell.
 20. The non-transitory computer-readable medium of claim 19,wherein modifying the time-based sequences of operations in order toprevent the one or more potential collisions comprises modifying one ormore positions between consecutive target positions within one or moreof the time-based sequences of operations.